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23fdf8178c
This implementation is based on __memset_power8 and integrates a lot of suggestions from Anton Blanchard. The biggest difference is that it makes extensive use of stxvl to alignment and tail code to avoid branches and small stores. It has three main execution paths: a) "Short lengths" for lengths up to 64 bytes, avoiding as many branches as possible. b) "General case" for larger lengths, it has an alignment section using stxvl to avoid branches, a 128 bytes loop and then a tail code, again using stxvl with few branches. c) "Zeroing cache blocks" for lengths from 256 bytes upwards and set value being zero. It is mostly the __memset_power8 code but the alignment phase was simplified because, at this point, address is already 16-bytes aligned and also changed to use vector stores. The tail code was also simplified to reuse the general case tail. All unaligned stores use stxvl instructions that do not generate alignment interrupts on POWER10, making it safe to use on caching-inhibited memory. On average, this implementation provides something around 30% improvement when compared to __memset_power8. Reviewed-by: Matheus Castanho <msc@linux.ibm.com> Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
/* Multiple versions of bzero. PowerPC64 version.
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Copyright (C) 2013-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Define multiple versions only for definition in libc. */
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#if IS_IN (libc)
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# include <string.h>
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# include <strings.h>
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# include "init-arch.h"
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extern __typeof (bzero) __bzero_ppc attribute_hidden;
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extern __typeof (bzero) __bzero_power4 attribute_hidden;
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extern __typeof (bzero) __bzero_power6 attribute_hidden;
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extern __typeof (bzero) __bzero_power7 attribute_hidden;
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extern __typeof (bzero) __bzero_power8 attribute_hidden;
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# ifdef __LITTLE_ENDIAN__
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extern __typeof (bzero) __bzero_power10 attribute_hidden;
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# endif
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libc_ifunc (__bzero,
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# ifdef __LITTLE_ENDIAN__
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(hwcap2 & (PPC_FEATURE2_ARCH_3_1 | PPC_FEATURE2_HAS_ISEL)
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&& hwcap & PPC_FEATURE_HAS_VSX)
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? __bzero_power10 :
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# endif
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(hwcap2 & PPC_FEATURE2_ARCH_2_07)
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? __bzero_power8 :
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(hwcap & PPC_FEATURE_HAS_VSX)
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? __bzero_power7 :
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(hwcap & PPC_FEATURE_ARCH_2_05)
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? __bzero_power6 :
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(hwcap & PPC_FEATURE_POWER4)
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? __bzero_power4
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: __bzero_ppc);
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weak_alias (__bzero, bzero)
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#endif
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